A Spokane gun dealer and four Washington residents who soon will be too young to buy semi-automatic rifles are among those filing a federal challenge to the state’s recently passed gun control measure.

Robin Ball, owner of the Sharp Shooting Indoor Range & Gun Shop, is among those joining with the National Rifle Association and the Second Amendment Foundation in a lawsuit that contends Initiative 1639 violates the U.S. Constitution and portions of federal law.

Although the results of the Nov. 6 election won’t be certified until Dec. 6, I-1639 is passing with nearly 60 percent of the vote and there aren’t enough uncounted ballots remaining to erase its lead of about 500,000 votes. The initiative restricts the sale of semiautomatic rifles to Washington residents who are at least 21, pass an enhanced background check and meet certain other requirements for training.

In a press release announcing the suit, foundation founder Alan Gottlieb said plaintiffs were “disappointed that too many voters were fooled into supporting this 30-page gun control scheme. This measure will have a chilling effect on the exercise of the constitutional rights of honest citizens while having no impact on criminals and we will not let it go unchallenged.”

Ball and a Vancouver gun dealer contend in the lawsuit the initiative violates the Commerce Clause of the Constitution because it will no longer allow them to sell those rifles to out-of-state residents. The lawsuit was filed in U.S. District Court in Seattle.

Four Washington residents, dubbed “Young Adult Plaintiffs” in the suit, are challenging the provisions that will keep them from buying a semiautomatic rifle before they turn 21. They include Nathaniel Casey, described in the lawsuit as a 19-year-old Spokane resident who attends Boise State University and is a member of the Army Reserves where he’s been trained on fully automatic weapons. Casey owns one semi-automatic rifle and has plans to purchase others, one for target practice and another for hunting.

The sales to those between 18 and 21 “impermissibly burdens the exercise of rights guaranteed by the Second Amendment,” the lawsuit claims, and is “significantly broader than necessary to serve any possible alleged government interest.”

Tallman Trask, a spokesman for the Yes on 1639 campaign, said he hasn’t seen the lawsuit because the state and the Attorney General Bob Ferguson are named as the defendants. Under state law, the attorney general’s office is responsible for defending initiatives the voters pass. But the campaign expected a lawsuit based on past challenges to other initiatives and could seek to intervene on the side of the state, Trask said.

“It’s the same thing they’ve done for years,” he said of the NRA and other gun-rights groups. “No matter what the challenges are, we’re committed to defending 1-1639.”

The NRA and the foundation had tried unsuccessfully to keep I-1639 off the ballot over questions about the way the full text of the measure was printed on the back of the petitions voters signed. The state Supreme Court ruled it should go on the ballot.